Combine cashews and water in a bowl. Cover and let stand at room temperature overnight.

Preheat oven to 350°. Drain and rinse cashews; transfer to a blender. Add almond milk; cover and blend until smooth. Set aside.

Cook green beans in enough lightly salted simmering water to cover for 8 to 12 minutes or until tender. Transfer beans to a large bowl of ice water. Cool; drain well. Transfer beans to a 3-quart baking dish; set aside.

For sauce, cook pancetta in a large skillet over medium-high heat until crisp. Remove pancetta from skillet and drain on paper towels; reserve drippings in skillet. Add mushrooms to skillet. Cook over medium heat for 5 minutes or until softened, stirring occasionally.

Remove skillet from heat. Add wine and shallots; return skillet to heat and bring to boil. Boil for 4 to 5 minutes or until wine evaporates. Add cashew mixture; bring to a simmer, stirring occasionally. Stir in mustard, 2 tablespoons basil, and 2 tablespoons dill; remove from heat.

Spoon mushroom mixture over beans. Sprinkle with pancetta and crispy onions. Bake for 20 minutes or until heated through. Garnish with additional basil and dill, if desired.